On Thu, Jan 17, 2013 at 10:48:15AM +0100, Linus Walleij wrote: > On Mon, Jan 7, 2013 at 11:44 AM, Mika Westerberg > <mika.westerb...@linux.intel.com> wrote: > > > In order to use DMA with this driver on non-PXA platforms we implement > > support > > for the generic DMA engine API. This allows to use different DMA engines > > with > > little or no modification to the driver. > > > > Request lines and channel numbers can be passed to the driver from the > > platform specific data. > > > > Signed-off-by: Mika Westerberg <mika.westerb...@linux.intel.com> > > --- > > drivers/spi/spi-pxa2xx.c | 351 > > +++++++++++++++++++++++++++++++++++++++- > > include/linux/spi/pxa2xx_spi.h | 6 + > > So if the other DMA implementation could go into spi-pxa2xx-pxadma.c > this could be spi-pxa2xx-dma.c and they could use the common header > file spi-pxa2xx-dma.h and then Kconfig select which one to compile. > > Just a suggestion to get the driver more readable.
Yes, it makes perfect sense. I'll do that in the next version. > > + /* > > + * Some DMA controllers have problems transferring buffers that are > > + * not multiple of 4 bytes. So we truncate the transfer so that it > > + * is suitable for such controllers, and handle the trailing bytes > > + * manually after the DMA completes. > > + */ > > + len = ALIGN(drv_data->len, 4); > > This is actually a property of the DMA controller. Right and this is not the proper place for this but I wasn't sure where to put this information... > struct dma_device already has this: > > * @copy_align: alignment shift for memcpy operations > * @xor_align: alignment shift for xor operations > * @pq_align: alignment shift for pq operations > * @fill_align: alignment shift for memset operations > (...) > u8 copy_align; > u8 xor_align; > u8 pq_align; > u8 fill_align; > > To align memcpy's on 4 bytes you can e.g. set .copy_align > to 2. > > So the syntax is number of shifts 1 << 2 = 4. > > If slave transfers can expose the same type of property we should > maybe introdyce .slave_align in the same manner so you don't have > to assume the worst in the driver. ... so this sounds good to me. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
